This invention relates to a printer, scanner, copier, facsimile machine, etc., particularly the paper feeding mechanism of the printer, etc. to automatically place the paper in position for printing.
Traditional paper feeding mechanism for a printer is shown in FIG. 1A. FIG. 1B shows the cross-sectional view of the feeding mechanism along the section line AAxe2x80x2 in FIG. 1A. The end of the paper tray 10 hangs out nearly horizontally as shown in FIG. 1B The front end of the paper tray 10 has a springboard 10A which presses against a conveying roller 14 by the spring 12. The conveying roller is driven by a rotating shaft 14A. The front of the of the paper tray has a recess 10D which allows the springboard 10A to jitter. The springboard 10A can tilt from an axis 10C from position 10A to position 10B when more paper P is stacked against the springboard 10A. The paper is positioned to provide contact CP between the paper P and the conveying roller 14. The friction between the roller 14 and the paper P causes the paper to be fed though the guide G to a next position. A friction plate 16 is pushed by a second spring 18 to make contact with the conveying roller. FIG. 1C shows the front end of the paper tray causing the springboard 10A to tilt to a position 10B when more paper lays over the spring board.
Conventional practice dictates that the paper be manually fed, so that the paper is properly positioned and not be misfed.
Another problem with conventional paper feeder is that more than one sheet of paper may be unintentionally fed at the same time due to pressure of the remaining stack of paper in the tray pushing the sheet of paper being fed. Such misfeeding may cause the successive sheets to stagger and the printout to be distorted.
An object of this invention is to automatically feed paper to a printer. Another object is to avoid misfeeding of paper in a printer. Still another object of this invention is to avoid human error in feeding paper to a printer. A further object of the present invention is to prevent more than one sheet of paper being fed at the same time.
These objects are achieved in this invention by using a resilient friction pad to push against a conveying roller. The resilient friction pad is housed in a recess at the front end of a paper tray. Each sheet of paper from the paper tray is conveyed one by one between the resilient friction pad and the conveying roller automatically.
To prevent more than one sheet of paper being fed at the same time, two springs are used to reduce the pressure of the sheets remaining in the tray.